case

I am in a tut which uses the term "case" in an updatePlayerAnimation function. I am unsure what "case means as when I search it I get other tuts but no definition. Any one have a quick explanation?

function updatePlayerAnimation()
{
   // Grab the desired direction of movement.
   %move = $moveRight - $moveLeft;
   %jump = $jump;
   
   // The state machine. The current state of the player is determined, and
   // based on some rules that can change that state, the state is updated.
   switch ($player.state)
   {
      // Standing still.
      case $playerStandState:
         // If suddenly the player is not a surface, start falling.
         if ($runSurface < 0)
            setPlayerState($playerStandFallState);